Technological Field
The present invention relates to an electrostatic charge image developing toner. More specifically, the present invention relates to an electrostatic charge image developing toner having compatibility between low-temperature fixing characteristics and high image storage property.
Description of the Related Art
Electrostatic charge image developing toners (hereinafter, simply referred to as “toner”) used in electrophotographic image formation should have reduced thermal energy during fixing of images to achieve a higher print rate and energy-saving image forming apparatuses. To satisfy this requirement, a toner having higher low-temperature fixing characteristics has been desired. It is known in the design of such a toner that a binder resin having sharp-melt characteristics, such as a crystalline polyester resin, is introduced into a particulate toner matrix to reduce the glass transition temperature or melt viscosity of the binder resin.
For example, it is known to use a binder resin mixture of an amorphous resin with a crystalline polyester resin having high compatibility with the amorphous resin. The combined use of such a crystalline polyester resin can enhance the low-temperature fixing characteristics of the toner because the crystalline polyester resin acts as a plasticizer during thermal fixing.
Other toners having low-temperature fixing characteristics are also known that are prepared as follows: Toner is prepared such that the particulate toner matrix contains crystal domains of a crystalline polyester resin, and the crystal domains are melted under thermal energy having a temperature higher than the melting point of the crystalline polyester resin during thermal fixing to be compatible with an amorphous resin (for example, see Japanese Patent Nos. 4729950 and 4742936).
Unfortunately, these toners are plasticized due to compatibilization of the amorphous resin with the crystalline polyester resin, resulting in reduced image storage property of fixed images after thermal fixing.